302 casting potential?

If it's going to be a mild build just clean them up with a good valve job and some gasket matching and run as is for now. Those heads will support 300HP in stock form. You can get power cheaper with bolt ons for a mild motor. Cam, manifold and headers with good exhaust and tune should get you more then stock 340 HP. Later when more money is available you can get serious with the mods.